wizard-campo-one2many

class CalculoPapelStart(ModelView):
    'Modelo Wizard Calculo Papel'
    _name = 'sale_imprenta.calculo.papel.start'

    producto_papel = fields.One2Many('product.template','products' ,u'Papel',
                        domain=[('category', '=', Id('sale_imprenta', 'cat_papel'))],
                        required=True, readonly=False,
                        )
CalculoPapelStart()


class CalculoPapel(Wizard):
    'Wizard Calcular Papel'
    _name = 'sale_imprenta.calculo.papel'

    start = StateView('sale_imprenta.calculo.papel.start',
    'sale_imprenta.calculo_papel_start_view_form', [
    Button('Cancelar', 'end', 'tryton-cancel'),
    Button('Siguiente', 'buscar_papel', 'tryton-go-next', True),
    ])

    buscar_papel = StateTransition()

    seleccion = StateView('sale_imprenta.calculo.papel.start',
    'sale_imprenta.calculo_papel_seleccion_view_form', [
    Button('Cancelar', 'end', 'tryton-cancel'),
    Button('Atras', 'volver_start', 'tryton-go-previous'),
    Button('Finalizar', 'terminar', 'tryton-ok', True),
    ])

    volver_start = StateTransition()

    def transition_buscar_papel(self, session):
        return 'seleccion'

    def default_seleccion(self, session, fields):
        pool = Pool()
        product_obj = pool.get('product.template')
        line_obj = pool.get('sale.line')
        product = product_obj.search([])
        pro = product_obj.browse(product)[0]

        res = {
            'producto_papel': {},
        }

        ## TODO: I want to relate some products to my One2Many field producto_papel
        res['producto_papel'].setdefault('add', [product])
        return res

    def transition_volver_start(self, session):
        return 'start'

    def transition_terminar(self, session):
        return 'end'

CalculoPapel()